Extreme sensitivity of the vortex state in a-MoGe films to radio-frequency electromagnetic perturbation

TL;DR

This study demonstrates that the vortex state in a-MoGe films is highly sensitive to radio-frequency electromagnetic perturbations, significantly affecting resistance in vortex fluid states, with implications for understanding vortex dynamics.

Contribution

It reveals the extreme sensitivity of vortex fluid resistance in a-MoGe films to low-amplitude radio-frequency electromagnetic perturbations.

Findings

Resistance increases by orders of magnitude with RF excitation.

Shielded samples show negligible resistance, indicating electromagnetic influence.

Vortex lattice melting occurs in two steps, from solid to fluid to liquid.

Abstract

Recently, detailed real space imaging using scanning tunneling spectroscopy of the vortex lattice in a weakly pinned a-MoGe thin film revealed that the vortex lattice melts in two steps with temperature or magnetic field, going first from a vortex solid to a hexatic vortex fluid and then from a hexatic vortex fluid to an isotropic vortex liquid. In this paper, we show that the resistance in the vortex fluid states is extremely sensitive to radio-frequency electromagnetic perturbation. In the presence of very low-amplitude excitation above few kilohertz, the resistance increases by several orders of magnitude. On the other hand when the superconductor is well shielded from external electromagnetic radiation, the dissipation in the sample is very small and the resistance is below our detection limit.